ISSN:
0947-6539
Keywords:
C-H activation
;
carbene complexes
;
cycloadditions
;
1,3-diamino-1,3-butadiene
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
2-Methyl-1,3-dimorpholino-1,3-butadiene 1 reacted with α,β-unsaturated Fischer carbene complexes to give a wide range of different products depending on the substitution pattern. Thus, sevenmembered rings (4, 5 and 6) could be obtained from chromium complexes 2 with aromatic or vinylic groups at the β position. Similar results were observed when α-methyl-substituted carbene complex 7 a was used. Six-membered carbocycles (derivatives of cycloadducts 12 and 13) were isolated after reaction with both chromium and tungsten complexes bearing one or two alkyl groups at the β position (10 and 11). Moreover, cyclopentenones 20 were the main products when the starting carbene complexes were alkyl-substituted at both α and β positions (19a, b) or when aromatic (19c, d) instead of vinylic complexes were used. A bicyclo[4.1.0]heptene system 18 has also been obtained in the special case of reaction with β,β-dimethylvinylchromium complex 13b; its formation could be explained as a formal carbene insertion into a C-H bond. The behaviour of diene 1 towards alkoxymethylcarbene complexes 22 was unusual. The different reaction products (cyclopentadienes 23, bicyclo[3.1.0]hexenes 24, aromatic amine 25 and metallatrienes 26) imply a mechanism in which the deprotonation of the carbene complex by the diene is followed by Michael addition to the iminium salt formed.
Additional Material:
5 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.19970031012
Permalink
